Halide perovskites is an emerging class of high-performance semiconductors which operate in the visible and infrared energy range. These old materials were recently popularized owing to the development of efficient photovoltaic devices, spearheaded by CH₃NH₃PbI₃. Starting from the modest 3% in 2009, halide perovskites can now consistently produce competitive power-conversion-efficiencies (PCE > 20%), thus representing one of the fastest developing solar cell technologies known to date. The remarkable physical properties of the halide perovskites stem from their unique electronic structure, which lends the semiconductors beneficial characteristics, such as high absorption coefficients and charge-carrier mobilities.

In this talk, the compositional space of the halide perovskites, AMX₃, (A⁺ = Cs, CH₃NH₃, HC(NH₂)₂); (M²⁺ = Ge, Sn, Pb); (X^- = Cl, Br, I) will be outlined and the structural chemistry of the materials will be detailed. The central role of the crystal structure, where small changes can significantly alter the optical, electrical and electronic properties of the perovskites will be discussed and the synthetic chemistry concepts that can “control” these subtle modifications will be elaborated. Furthermore, following the dimensional reduction principle, the synthesis and properties of low dimensional systems such as “hollow” perovskites, two dimensional perovskites and perovskite polytypes will be discussed.